Method And Device For Regulating The Temperature And Relative Humidity In A Building

ABSTRACT

A method and device are provided for regulating the temperature and relative humidity of the air in a building having microporous external walls and external thermal insulation, including air circulation spaces provided between the walls and the thermal insulation, and a device for supplying the spaces with a controlled air flow, the device configured for supplying the spaces with air substantially saturated with water vapour.

The invention relates to a method and a device for regulating the temperature and the relative humidity of the air inside a building, for example a residence or another type, commercial, industrial, offices or other.

In document FR2933479-A1, in order to reduce the energy consumption of a building for its heating and its air conditioning, it has already been proposed to install an external thermal insulation on the microporous external walls of the building by arranging air circulation spaces between these walls and the thermal insulation, and to circulate external air in these spaces in order to selectively heat or cool the external walls via absorption or evaporation of water, the walls being made of stone, bricks, concrete blocks, etc., which are naturally microporous materials.

In the summer, the external air has a relatively high temperature and, during certain periods of the day or of the night, a low relative humidity. When this air comes into contact with a wall of the building, a certain quantity of water contained in the microporous material of the wall is vaporised and absorbed by the external air present in the aforementioned space, which cools the wall and tends to reduce the temperature inside the building and also to stabilise the relative humidity in the building. The external air present in the aforementioned space, which is loaded with water vapour, is discharged to the outside.

In the winter, the external air which is admitted into the aforementioned spaces must have a high relative humidity. However, this occurs when the external temperature is at its lowest. The number of times when the external air can be admitted in the aforementioned spaces to heat the walls is therefore limited. This nevertheless remains possible because the thermal capacity of the air is substantially less than that of the walls. It is required however that there is not a rapid renewal of the external air in these spaces because then the convection effect would prevail over the heating effect via condensation of the water vapour of the external air.

When cold external air with high relative humidity is admitted in the aforementioned spaces, the walls in contact with this air absorb a portion of the water vapour of the external air and are heated by the latent condensation heat of the water vapour. A surface temperature of the walls on the “air gap” side is then obtained which is higher than the temperature setting in the building (for example 20° C.). A thermal heating flow is as such generated in the walls, which tends to compensate the overall heat losses in the building and to respect the temperature setting. The relative humidity of the air inside the building also tends to increase.

It has been possible to check with a control residence that the annual cost of the energy consumption for the regulating of the temperature to about 20° C. inside the building is as such reduced by about 75% in the Midi-Pyrenees region.

However, in the winter, when the temperature of the external air is less than 5° C., the heating of the walls by the condensation of the water vapour of the external air can be substantially cancelled by the cooling via convection of the walls in contact with the cold air, and the aforementioned system loses its effectiveness.

The invention aims in particular to provide a simple, efficient and economical solution to this problem.

It proposes for this purpose a method for regulating the temperature and the relative humidity of the air in a building with microporous walls and with external thermal insulation, wherein air circulation spaces are arranged between the external thermal insulation and the walls, characterised in that it consists in regulating the relative humidity of the air that is admitted in said spaces, by heating or by cooling and/or by passing through humidifying means arranged upstream of the air circulation spaces.

The cooling of the air that will be admitted in the aforementioned spaces makes it possible for example to change its relative humidity from 40 or 50% to 90 or 95% when its temperature is reduced from 20° C. to about 14° C. This cooling can be done advantageously via heat exchange, therefore without consuming energy, between the air extracted from the building and the air taken from outside the building. Inversely, if it is desired to admit air having a lower relative humidity in the aforementioned spaces, this air can be heated via heat exchange between the air taken from inside the building and air taken from outside the building.

The humidifying means make it possible to increase notably the relative humidity and the absolute humidity of the air admitted in the aforementioned spaces, in order to favour as much as possible the absorption and the condensation of water vapour in these walls and the resulting heating effect. In addition, the heating cycles can be repeated more frequently and distributed over 24 hours. Advantageously, the “humidified” air which is admitted in the aforementioned spaces is not external air, but air taken from inside the building or a mixture of air taken from inside the building and of air taken from outside the building.

This is filtered air, cleaner than the external air, which is as such admitted in the aforementioned spaces, which prevents a progressive clogging of the micropores of the walls with dust and similar matter contained in the external air.

The air taken from inside the building has, in the winter, a temperature of about 18 to 20° C. and a rather low relative humidity, for example 40%. The passing of this air in the humidifying means makes it possible to increase its relative humidity to a rate of about 90% to 95%, the temperature of this air being lowered to about 14° C. when the humidifying means are of the adiabatic type. The absolute humidity of the air is also increased, with the quantity of water contained in the air passing for example from 4.31 g of water per kg of dry air to 9.64 g/kg of dry air, which makes it possible to recover a larger quantity of heat via condensation of the water vapour and/or to extend the duration of the heating cycle.

In the winter, air can as such be circulated at 14° C. and at least 90% of relative humidity in the spaces between the external thermal insulation and the walls of the building, which results in a supply of thermal energy that is more substantial inside the building and by a maintaining of the relative humidity of the air inside the building at about 60%, which gives a greater sensation of comfort to the people in the building.

In an advantageous embodiment of the invention, the air to be humidified is passed in a hot water tank, more preferably with solar or geothermal or energy recovery heating, for example with a stove, with a chimney, in an industrial building or in a shopping centre, etc. or any other means of free energy. The passage in these humidifying means of the air intended to be admitted in the aforementioned circulation spaces, makes it possible to both increase the relative humidity of the air substantially until saturation and increase its temperature, without however substantially lowering the temperature of the water in the tank. A source of wet and hot air is as such available making it possible to maintain a temperature and humidity desired in the building, in the winter and regardless of the climate of the region where the building is located. According to another characteristic of the invention, the air substantially saturated with humidity that exits the humidifying means, is intermittently blown inside the building.

This makes it possible, in winter, to very quickly increase the relative humidity of the air inside the building, for example to about 60%, which results in a greater sensation of comfort, without however increasing the temperature of the air which remains substantially constant inside the building.

The invention also proposes a device for regulating the temperature and the relative humidity of the air inside the building with microporous walls and with external thermal insulation, comprising means for controlling the intake of air in the spaces arranged between the external thermal insulation and the microporous walls, characterised in that it further comprises means for regulating at a desired value the relative humidity of the air admitted in the aforementioned spaces, by heating or by cooling or by passing in humidifying means.

These means can include a heat exchanger in order to modify the temperature of this air and consequently its relative humidity, and/or means for humidifying air of which an outlet is connected to an inlet of said air circulation spaces, with these humidifying means comprising for example a hot water tank heated by a free source of energy or heat recovery.

This device is also characterised in that it comprises means for supplying the humidifying means with air taken from outside the building or with air taken from inside the building or with a mixture of air taken from outside the building and of air taken from inside the building.

Advantageously, the means of humidifying the air are supplied with air via a double-flow controlled mechanical ventilation installation, comprising means for sucking air inside and outside the building, and means for blowing air inside the building and in said spaces between the walls and the external thermal insulation. In an embodiment of the invention, the controlled mechanical ventilation installation comprises at the outlet a two-channel caisson, connected respectively to air inlet means inside the building and to air inlet means in the air circulation spaces between the walls and the thermal insulation.

For example, the means for humidifying air are mounted between means for exchanging heat between the air taken from inside the building and the air taken from outside the building, and means of backup heating of the blown air.

Generally, the invention makes it possible to provide a regulation of the temperature and of the relative humidity of the air inside a building, all throughout the year without consuming any energy, except for that which may be required for the operation of the means for humidifying, sucking and blowing air and for a backup heating of the air blown in the building. The energy savings thus made exceed 65% and can reach 100% in regions that benefit from a temperate climate.

The invention shall be better understood and other characteristics, details and advantages of the latter shall appear more clearly when reading the following description, provided by way of an unrestricted example in reference to the annexed drawings wherein:

FIG. 1 is a partial cross-section diagrammatical view of a building provided with a device according to the invention;

FIG. 2 is a front diagrammatical view of a portion of the building of FIG. 1;

FIG. 3 is a diagrammatical view of the device according to the invention.

FIGS. 1 and 2 diagrammatically show a portion of a building 10, for example of a residence or of offices, or a commercial, industrial or other building, which comprises external walls 12 and a roof 14, with the external walls 12 being provided with an external thermal insulation 16 which arranges with the external surface of the walls 10 air circulation spaces 18 or “air gaps”.

The external walls 12 of the building have a microporous structure and can be made with common products that naturally have a microporous structure, such as for example bricks, concrete blocks, stones, etc.

The thermal insulation 16 which is added onto the external surface of the walls 12 is of any suitable type and is installed in such a way as to arrange with the walls 12 the spaces 18 which have a thickness of a few centimetres and which extend more preferably over the entire external surface of the walls 12.

More preferably, as shown in FIG. 2 which is a front view of a wall 12 comprising a window F, the spaces 18 each comprise a series of vertical channels delimited by horizontal and vertical slats 20, with the channels communicating with their ends, in such a way that the air circulates in a channel by descending along a wall 12 then rising up along this wall in the following channel and so on.

Valves 22 for controlling the inlet of air and the outlet of air are mounted in the air intakes and outlets respectively, at the right and left ends and at the upper end of the space 18, with these valves being advantageously of the closed type at rest and open via an overpressure of air.

The air circulation spaces 18 are supplied with air by a device 24 shown in more detail in FIG. 3.

This device substantially comprises a double-flow controlled mechanical ventilation installation 26, which is associated to humidifying means 28, to means 30 of backup heating and, if needed, for drying air, and to means 32 for distributing the air towards the aforementioned spaces 18 or towards the air blower outlets inside the building.

The controlled mechanical ventilation installation 26 comprises, generally, a heat exchanger 34 comprising a primary circuit wherein circulates air 36 extracted from the building and a secondary circuit wherein circulates fresh air 38 taken from outside the building. Means 40 for by-passing are provided in the exchanger 34 in order to deliver, at the outlet of this exchanger, either fresh air taken from outside the building and which has been heated via heat exchange with the air 36 extracted from the building, or fresh air not heated by the extracted air, or a mixture of fresh air 38 and of air 36 extracted from the building.

The heat exchanger 34 makes it possible to regulate the relative humidity of the air that passes through it, via cooling when it is desired to increase this humidity or via heating if it is desired to decrease this humidity.

The outlet of the heat exchanger 34 supplies the humidifying means 28 which are more preferably of the adiabatic type, and for example with ultrasound. These humidifying means make it possible to raise the relative humidity of the air that passes through it, for example from 40% to about 90% or 95%, i.e. to practically saturate this air with water vapour and to increase absolute humidity notably.

When this humidification is adiabatic, it is accompanied by a drop in the temperature of the air, which passes for example from 18-20° C. to about 14° C.

The air exiting the humidifying means 28 can be admitted if necessary into the means 30 for backup heating, which are more preferably means of electric or heat recovery heating and which have a relatively low energy consumption, for example from 2 to 3 kWh for a residential building 10 of a common average size (for example 100 to 130 m² of liveable space).

Means 42 for sucking air and 44 for blowing air, such as fans, are mounted respectively at the outlet of the primary circuit of the exchanger 26, for the discharging to the outside of air 36 taken from inside the building, and at the outlet of the means of backup heating 30 for the blowing of air in the means for distributing 32.

These means for distributing are advantageously comprised of a caisson provided with two air outlets, one 46 being intended to supply air circulation spaces 18 between the walls 12 and the external thermal insulation 16, and the other 48 the blowing of air inside the building 10.

The device 24 further comprises a certain number of usual pieces of equipment such as filters for example, which have not been shown on the drawing for increased clarity.

This device operates in the following manner:

In the summer, when the external air has a relatively high temperature, for example of at least 25° C., and a low relative humidity, for example less than 40%, the device according to the invention is controlled in order to maintain inside the building a temperature less than 25° C., for example in the vicinity of 22° C., and a relative humidity of the air of about 60%, which corresponds to a pleasant sensation of comfort. For this, external air is taken from outside the building and is directly injected in the spaces 18 arranged between the walls 12 and the external thermal insulation 16. The circulation of the air at low speed in the spaces 18 allows for an absorption by the air of the humidity contained in the walls 12 and the cooling of these walls via evaporation of a portion of the water that they contain.

As explained in detail in the prior patents of the Applicant, the microporous walls 12 constantly absorb a portion of the humidity of the air inside the building and transfer this humidity to the air that circulates in the spaces 18, which results in a decrease in the temperature and in the relative humidity of the air inside the building.

In order to maintain a relative humidity of the air in the vicinity of 50 to 60% inside the building, the device 24 makes it possible to intermittently blow, inside the building, external air which is passed in the humidifying means 28 and of which the relative humidity was raised from 30 or 40% to about 90% or 95%. As such a sensation of comfort is maintained inside the building, by preventing the relative humidity of the air in the building from becoming too low for a given temperature, which would result in a sensation of cold.

The device 24 can also be used to circulate external air at a higher greater speed in the spaces 18, in particular during the night, when the external air is at a temperature lower than 20° C. The walls 12 can as such be cooled via convection.

It is also possible, intermittently, to blow relatively cold external air inside the building, for example when the heat was very high during the day, in order to evacuate the calories.

In the winter, when the external air is at a relatively low temperature, for example at 5° C., it is advantageous to circulate in the spaces 18 the air 36 taken from inside the building and of which the relative humidity has been raised to a value of about 90% or 95%, via simple heat exchange with the cold external air in the exchanger 34 of the installation 26, and/or by passing in the humidifying means 28. A mixture of air 36 taken from inside the building and of fresh air 38 taken from outside the building can also be admitted in the spaces 18.

Air at a temperature of 14° C. for example, having a relative humidity of 90% to 100% and a substantial absolute humidity can as such be brought into the spaces 18. The circulation of this air in the spaces 18 is done at a relatively low speed or intermittently, in such a way that the walls 12 can be recharged with humidity and be heated by the latent condensation heat of the water vapour of the air which was brought in the spaces 18. The walls 12 as such constantly transfer heat and humidity to the air contained in this building, which raises its temperature and its relative humidity.

The means 30 of backup heating make it possible, if required, to rapidly inject a large quantity of hot air inside the building, this air being blown via the outlet 48 of the caisson 32.

As shown diagrammatically in FIG. 3, the humidifying means 28 can be supplied directly with air 36 taken from inside the building, without this air first passing through the heat exchanger 34.

In the example embodiment wherein the device 24 is installed in a residential house of average size, the controlled mechanical ventilation installation 26 makes it possible to inject inside the house a fresh air flow 38 preheated via heat exchange with the extracted air 36 in the exchanger 34, of about 150 m3/h for the renewal of air in the house, with the fans 42 and 44 then being driven at low speed.

The renewal of the air contained in the spaces 18 can be provided in a few minutes by the installation 26, with a treated air flow varying from 150 to 500 m3/h, with the humidifying means 30 able to provide an air flow of 500 m3/h with a relative humidity of about 60% and a temperature of about 20° C. in the building. The device according to the invention can supply a thermal power of about 100 W/m² for 15 minutes every 2 hours, via condensation of the water vapour contained in the air present in the spaces 18.

When the installation 26 is used as backup heating by blowing of air in the house, the treated air flow is for example 500 m3/h, comprising 150 m3/h of fresh air 38 and 350 m3/h of extracted air 36, with the air being heated by the means 30 having an electrical power of 2 to 3 kW.

In a particularly advantageous embodiment of the invention, the humidifying means 28 include a hot water tank, for example at a temperature of about 60 to 65° C., wherein is made to pass the air that will circulate in the aforementioned spaces 18.

This hot water tank is associated to means of heating which include more preferably a free source of heat, for example means of heating with solar or geothermal energy or means of heat recovery on a chimney, on a wood stove, in the industrial environment, in a large shopping centre, etc. according to the type of building concerned.

The air can circulate in the hot water tank at the surface of the water or through the water contained in the tank. At least a portion of the air extracted from the building can be passed in the tank in order to saturate it with humidity before injecting it in the aforementioned spaces 18. In the case of a residential building intended for the lodging of four people, the hot water tank typically has a volume of about 150 to 250 litres, the hot water is at a temperature of about 60° C. and the volume of air treated can be about 300 m3/h, with a relative humidity of 90 to 95% and a temperature from 16 to 21° C. when it is injected into the spaces 18, with the decrease in the temperature of the hot water in the tank being about 3 to 7° C. according to the conditions of passage of the air in the tank.

During the cold season, a means is thus available that makes it possible to provide the heating of the building and the regulating of the relative humidity inside the building without consuming practically any electrical energy.

Generally, the device 24 according to the invention makes it possible, thanks to the heat exchanger 34 and/or to the humidifying means 28, to supply the spaces 18 between the walls 12 and the external thermal insulation 16 with air which is substantially saturated with humidity, and to blow air saturated with humidity inside the building when it is required to raise the relative humidity of the air in the building for a greater sensation of comfort. The blowing of air saturated with humidity in the spaces 18 between the walls and the external thermal insulation makes it possible to provide the heating inside the building and the maintaining of a substantially constant temperature of about 20° C. inside the building, regardless of the outside climatic conditions, and this at a price of electrical energy consumption that is very low or practically zero. 

1. Method for regulating the temperature and the relative humidity of the air in a building with microporous walls and with external thermal insulation, air circulation spaces being arranged between the external thermal insulation and the walls, which it consists in regulating the relative humidity of the air admitted into said spaces, via heating or via cooling and/or by passing in humidifying means arranged upstream of the air circulation spaces.
 2. Method according to claim 1, wherein it consists in passing in the humidifying means fresh air taken from outside the building, or air extracted from the building or a mixture of fresh air taken from outside and of air extracted from the building.
 3. Method according to claim 1, wherein the air exiting the humidifying means is intermittently blown inside the building in order to increase the relative humidity of the air in the building.
 4. Method according to claim 1, wherein the air exiting the humidifying means is substantially saturated with water vapour.
 5. Device for regulating the temperature and the relative humidity of the air inside a building with microporous walls and with external thermal insulation, comprising means for controlling the intake of air into spaces arranged between the external thermal insulation and the microporous walls, wherein it further comprises means for regulating at a desired value the relative humidity of the air admitted in the aforementioned spaces, via heating or via cooling or by passing in humidifying means.
 6. Device according to claim 5, wherein the humidifying means include a hot water tank and means for heating water with solar or geothermal energy or heat recovery.
 7. Device according to claim 5, wherein it comprises means for supplying humidifying means with air taken from outside the building or with air taken from inside the building or with a mixture of air taken from outside the building and of air taken from inside the building.
 8. Device according to claim 6, wherein the humidifying means are supplied with air by a double-flow controlled mechanical ventilation installation, comprising means for sucking air inside and outside the building and for blowing air inside the building and in said spaces between the walls and the external thermal insulation.
 9. Device according to claim 8, wherein the controlled mechanical ventilation installation comprises at the outlet a caisson with two channels connected respectively to air inlet means in said spaces and to air inlet means inside the building.
 10. Device according to claim 8, wherein the humidifying means are mounted between means for exchanging heat between the air taken from outside the building and the air taken from inside the building, and means of backup heating of the blown air. 